The present disclosure relates to an image processing apparatus, an image processing method, an information recording medium, and a program, and more particularly, an image processing apparatus and method for performing image blur correction, an information recording medium, and a program.
In an image photographed by an imaging apparatus such as a digital camera, for example, noise or blurring occurs due to focus shift, lens aberration, and further noise occurring in a CCD, a CMOS and the like, which are imaging elements.
Particularly, in a camera using an inexpensive lens, blurring of an image is severe due to lens aberration as an image height (a distance from an optical center) increases.
A correction process of noise or blurring of an image caused by various factors as described above has been disclosed in the related arts, for example, Japanese Unexamined Patent Application Publication No. 2006-246080, Japanese Unexamined Patent Application Publication No. 2009-159603, Japanese Unexamined Patent Application Publication No. 2010-081263, and the like.
Japanese Unexamined Patent Application Publication No. 2006-246080 discloses a correction process configuration using sharpening parameters differing in units of areas of a photographed image. In detail, image correction is performed by enhancing the sharpening parameters as an image height (a distance from an optical center) increases.
However, since the process of Japanese Unexamined Patent Application Publication No. 2006-246080 corresponds to only a process for enhancing the magnitude of a high frequency component according to an image height, and for example, does not consider a change and the like in frequency characteristics of magnification chromatic aberration or blurring, there is a problem that appropriate correction may not be performed.
Furthermore, Japanese Unexamined Patent Application Publication No. 2009-159603 discloses a configuration in which, in order to cope with blurring changed by individual differences or manufacturing errors of lenses, filters are selected according to respective lens characteristics and a blur correction process is performed.
However, if the correction process is applied to blur with a blur pattern continuously changing according to an image height as with the aforementioned image height-dependent blur, there is a problem that the number of types of filters for blur correction is huge.
Moreover, Japanese Unexamined Patent Application Publication No. 2010-081263 discloses a configuration in which filters whose positions of center of gravity are shifted in respective image heights are applied to so-called partial blur indicating a blur pattern in which unevenness occurs due to the image heights, so that appropriate correction is performed according to the image heights.
In detail, correction corresponding to the partial blur is performed by correcting the positions of the center of gravity of the filters. However, since the positions of the center of gravity are mainly corrected, control of correction magnitude is not shown, and individual processes corresponding to a very blurred part and a less blurred part are not performed, appropriate correction may not be performed.
Moreover, Japanese Unexamined Patent Application Publication No. 2011-055038 discloses a correction process for a photographed image of an imaging apparatus provided with a filter having an RGBW array including a full wavelength transmission white (W) pixel as well as each RGB color as a filter subordinate to an imaging element.
In the case of using the filter having the RGBW array including the white (W) pixel, since the W pixel transmits visible rays with a wide wavelength region, a blur pattern is changed according to an object color.
In the process of Japanese Unexamined Patent Application Publication No. 2011-55038, uniform correction not dependent on an object color is performed, but there is a problem that a correction effect may not be sufficiently obtained for a blur pattern changed according to the object color.
Furthermore, in most configurations of the aforementioned related arts, for example, pixel value correction is performed based on filtering using a convolution operation. However, in order to perform various types of correction, since the configurations require many filters for performing the filtering and a large storage capacity memory, there is a problem that it is difficult for a small and inexpensive camera to employ the configurations.